The present invention is related to the field of isocyanate based thermoset polymers. More specifically, the present invention is related to compositions prepared using isocyanate based thermoset polymers.
Isocyanate based thermoset polymers are commonly prepared for many purposes. For example, automobile fascia, body panels and structural components are often formed from these materials, frequently by means of reaction injected molding. However, molding of these and similar structures often results in significant amounts of thermoset scrap materials.
These scrap materials arise from certain characteristic aspects of the molding process. For example, overfilling of the mold, to reduce the incidence of voids, is often desirable. However, the excess polymer in this instance forms flash, which heretofore has generally been waste material. Scrap is also produced due to the nature of the reaction injection molding process. Typically, an isocyanate-based liquid stream is impingement mixed with an active hydrogen containing liquid stream. The polymerizing mixture is then guided into a mold via a sprue and gate. The sprue and gate is ultimately cut off prior to use, and again represents waste material.
Other sources of scrap also exist. These include, for example, isocyanate based thermoset materials which show defects in paint finishing or molding and the like. At present, from about 5 to about 15 percent of the automotive reaction injected molded parts are designated as scrap and are commonly landfilled at great expense to the manufacturer.
As in the case of reaction injection molded thermoset polymers, the formation of isocyanate based flexible slabstock polymer foams and the subsequent fabrication of such foams into useful articles also results in scrap and resultant waste. Some researchers estimate that up to 25 percent of flexible slabstock polymer foams end up as cutting scraps. (See, e.g., G. Oertel, ed., Polyurethane Handbook, Hanser Publishers (Munich 1985) 176.) Other sources of isocyanate-based thermoset polymer scrap include, for examples overflow from molded foams and cast elastomers; cutting scrap and overflow from rigid foams; fiber production scrap; and flashy sprue and gate scrap from structural reaction injection molding and reinforced reaction injection molding.
In view of the above facts efforts are being made to find ways to recycle these scrap materials. For examples U.S. Pat. Nos. 3,738,946 and 3,708,440 describe the hydrolytic conversion of parts made from thermoset polymers back into polyols and/or polyamines for reuse in rigid foam applications. U.S. Pat. Nos. 4,514,530; 4,552,933; and 4,578,412 disclose the use of solutions of pulverized parts in polyamines for thermoset-type molded parts. U.S. Pat. No. 3,935,132 discloses the use of blends of thermoplastic polyurethanes and pulverized thermoset reaction injection molded (RIM) parts to manufacture extruded or molded parts. U.S. Pat. No. 4,439,546 discloses the use of scrap isocyanate-based thermoset reaction injection molded polymers in blends with recycled polyethylene terephthalate polyols in the preparation of rigid foams. Other researchers have also suggested the incineration of scrap thermoset RIM parts to yield heat energy or electrical energy. These methods of recycling thermoset materials offer opportunities to reduce scrap and therefore the resultant waste and expense, but do not entirely solve the scrap problem.
Thus, it would be desirable, from an economic, environmental and commercial standpoint, to develop additional means by which scrap material, particularly isocyanate based thermoset polymeric material, can be converted into a useful resource. Such means would preferably be able to be employed onsite at manufacturing facilities.